青藏高原古地理环境研究

Progress in paleogeographic study of the Tibetan Plateau

本文综述了最近 5 0年青藏高原古地理演化中一些基本问题研究进展。分析了中新世～上新世青藏古地理环境 ,高原在 3 6MaBP海拔不超过 10 0 0m ,此后强烈隆升。青藏高原最近三次冰期年代分别为 72 5～ 5 81、 2 89～ 136、 82～ 10kaBP ,冰期中不存在“大冰盖”。高原晚新生代重大古地理演化阶段和事件为 :38～ 2 2MaBP行星风系控制的热带 亚热带低地、 2 2～3 6MaBP古季风出现与主夷平面发育、 3 6～ 1 7MaBP高原强烈隆升与现代季风形成和现代河谷发育、 1 1～ 0 6MaBP高原抬升进入冰冻圈与大冰期出现、 0 15MaBP以来强烈隆升与高原内部干旱化。

This article summarizes research progress in some basic problems on paleogeographic revolution of the Tibetan Plateau in the last 50 years, especially recent decade. Based on reviews of current viewpoints and analysis of Miocene and Pliocene paleogeographies, it was suggested that altitude of the Tibetan Plateau was less than 1000m before 3.6Ma BP and intense uplift of the plateau began at that time. The ages of last three glaciations in the plateau are 725～581,289～136 and 82～10ka BP respectively, which are comparable with oxygen isotopic stages in deep sea. Large ice sheet did not exist in the Tibetan Plateau in the Maximum Glaciation of Pleistocene. Environmental changes were frequent with high amplitude and desiccation occurred in the Tibetan Plateau since the last interglacial period. Important phases and events of paleogeographic evolution in Cenozoic are: tropical and subtropical lowland controlled by planetary wind system between 38 and 22Ma BP, appearance of paleo-monsoon and development of main planation surface between 22 and 3.6Ma BP, intense uplift resulting in the formation of the modern monsoon and development of water system between 3.6 and 1.7Ma BP, entrance of cryosphere and maximum glaciation between 1.1 and 0.6Ma BP, and intense uplift and desiccation of climate in the inner plateau. Finally, some important problems need to be researched in future are suggested. It is indicated that key to breakthroughs in paleogeographical research lies in analysis of depositional basins and stratified landforms in and around the plateau, precise dating and explanation of high-resolution environmental information.